// Copyright Joyent, Inc. and other Node contributors.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to permit
// persons to whom the Software is furnished to do so, subject to the
// following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE.


var isWindows = process.platform === 'win32';


// resolves . and .. elements in a path array with directory names there
// must be no slashes, empty elements, or device names (c:\) in the array
// (so also no leading and trailing slashes - it does not distinguish
// relative and absolute paths)
function normalizeArray(parts, allowAboveRoot) {
    // if the path tries to go above the root, `up` ends up > 0
    var up = 0;
    for (var i = parts.length - 1; i >= 0; i--) {
        var last = parts[i];
        if (last == '.') {
            parts.splice(i, 1);
        } else if (last === '..') {
            parts.splice(i, 1);
            up++;
        } else if (up) {
            parts.splice(i, 1);
            up--;
        }
    }

    // if the path is allowed to go above the root, restore leading ..s
    if (allowAboveRoot) {
        for (; up--; up) {
            parts.unshift('..');
        }
    }

    return parts;
}


if (isWindows) {
    // Regex to split a windows path into three parts: [*, device, slash,
    // tail] windows-only
    var splitDeviceRe =
        /^([a-zA-Z]:|[\\\/]{2}[^\\\/]+[\\\/][^\\\/]+)?([\\\/])?([\s\S]*?)$/;

    // Regex to split the tail part of the above into [*, dir, basename, ext]
    var splitTailRe = /^([\s\S]+[\\\/](?!$)|[\\\/])?((?:\.{1,2}$|[\s\S]+?)?(\.[^.\/\\]*)?)$/;

    // Function to split a filename into [root, dir, basename, ext]
    // windows version
    var splitPath = function(filename) {
        // Separate device+slash from tail
        var result = splitDeviceRe.exec(filename),
            device = (result[1] || '') + (result[2] || ''),
            tail = result[3] || '';
        // Split the tail into dir, basename and extension
        var result2 = splitTailRe.exec(tail),
            dir = result2[1] || '',
            basename = result2[2] || '',
            ext = result2[3] || '';
        return [device, dir, basename, ext];
    };

    // path.resolve([from ...], to)
    // windows version
    exports.resolve = function() {
        var resolvedDevice = '',
            resolvedTail = '',
            resolvedAbsolute = false;

        for (var i = arguments.length - 1; i >= -1; i--) {
            var path;
            if (i >= 0) {
                path = arguments[i];
            } else if (!resolvedDevice) {
                path = process.cwd();
            } else {
                // Windows has the concept of drive-specific current working
                // directories. If we've resolved a drive letter but not yet an
                // absolute path, get cwd for that drive. We're sure the device is not
                // an unc path at this points, because unc paths are always absolute.
                path = process.env['=' + resolvedDevice];
                // Verify that a drive-local cwd was found and that it actually points
                // to our drive. If not, default to the drive's root.
                if (!path || path.slice(0, 3).toLowerCase() !==
                    resolvedDevice.toLowerCase() + '\\') {
                    path = resolvedDevice + '\\';
                }
            }

            // Skip empty and invalid entries
            if (typeof path !== 'string' || !path) {
                continue;
            }

            var result = splitDeviceRe.exec(path),
                device = result[1] || '',
                isUnc = device && device.charAt(1) !== ':',
                isAbsolute = !!result[2] || isUnc, // UNC paths are always absolute
                tail = result[3];

            if (device &&
                resolvedDevice &&
                device.toLowerCase() !== resolvedDevice.toLowerCase()) {
                // This path points to another device so it is not applicable
                continue;
            }

            if (!resolvedDevice) {
                resolvedDevice = device;
            }
            if (!resolvedAbsolute) {
                resolvedTail = tail + '\\' + resolvedTail;
                resolvedAbsolute = isAbsolute;
            }

            if (resolvedDevice && resolvedAbsolute) {
                break;
            }
        }

        // Replace slashes (in UNC share name) by backslashes
        resolvedDevice = resolvedDevice.replace(/\//g, '\\');

        // At this point the path should be resolved to a full absolute path,
        // but handle relative paths to be safe (might happen when process.cwd()
        // fails)

        // Normalize the tail path

        function f(p) {
            return !!p;
        }

        resolvedTail = normalizeArray(resolvedTail.split(/[\\\/]+/).filter(f),
            !resolvedAbsolute).join('\\');

        return (resolvedDevice + (resolvedAbsolute ? '\\' : '') + resolvedTail) ||
            '.';
    };

    // windows version
    exports.normalize = function(path) {
        var result = splitDeviceRe.exec(path),
            device = result[1] || '',
            isUnc = device && device.charAt(1) !== ':',
            isAbsolute = !!result[2] || isUnc, // UNC paths are always absolute
            tail = result[3],
            trailingSlash = /[\\\/]$/.test(tail);

        // Normalize the tail path
        tail = normalizeArray(tail.split(/[\\\/]+/).filter(function(p) {
            return !!p;
        }), !isAbsolute).join('\\');

        if (!tail && !isAbsolute) {
            tail = '.';
        }
        if (tail && trailingSlash) {
            tail += '\\';
        }

        return device + (isAbsolute ? '\\' : '') + tail;
    };

    // windows version
    exports.join = function() {
        function f(p) {
            return p && typeof p === 'string';
        }

        var paths = Array.prototype.slice.call(arguments, 0).filter(f);
        var joined = paths.join('\\');

        // Make sure that the joined path doesn't start with two slashes
        // - it will be mistaken for an unc path by normalize() -
        // unless the paths[0] also starts with two slashes
        if (/^[\\\/]{2}/.test(joined) && !/^[\\\/]{2}/.test(paths[0])) {
            joined = joined.slice(1);
        }

        return exports.normalize(joined);
    };

    // path.relative(from, to)
    // it will solve the relative path from 'from' to 'to', for instance:
    // from = 'C:\\orandea\\test\\aaa'
    // to = 'C:\\orandea\\impl\\bbb'
    // The output of the function should be: '..\\..\\impl\\bbb'
    // windows version
    exports.relative = function(from, to) {
        from = exports.resolve(from);
        to = exports.resolve(to);

        // windows is not case sensitive
        var lowerFrom = from.toLowerCase();
        var lowerTo = to.toLowerCase();

        function trim(arr) {
            var start = 0;
            for (; start < arr.length; start++) {
                if (arr[start] !== '') break;
            }

            var end = arr.length - 1;
            for (; end >= 0; end--) {
                if (arr[end] !== '') break;
            }

            if (start > end) return [];
            return arr.slice(start, end - start + 1);
        }

        var toParts = trim(to.split('\\'));

        var lowerFromParts = trim(lowerFrom.split('\\'));
        var lowerToParts = trim(lowerTo.split('\\'));

        var length = Math.min(lowerFromParts.length, lowerToParts.length);
        var samePartsLength = length;
        for (var i = 0; i < length; i++) {
            if (lowerFromParts[i] !== lowerToParts[i]) {
                samePartsLength = i;
                break;
            }
        }

        if (samePartsLength == 0) {
            return to;
        }

        var outputParts = [];
        for (var i = samePartsLength; i < lowerFromParts.length; i++) {
            outputParts.push('..');
        }

        outputParts = outputParts.concat(toParts.slice(samePartsLength));

        return outputParts.join('\\');
    };


} else /* posix */ {

    // Split a filename into [root, dir, basename, ext], unix version
    // 'root' is just a slash, or nothing.
    var splitPathRe = /^(\/?)([\s\S]+\/(?!$)|\/)?((?:\.{1,2}$|[\s\S]+?)?(\.[^.\/]*)?)$/;
    var splitPath = function(filename) {
        var result = splitPathRe.exec(filename);
        return [result[1] || '', result[2] || '', result[3] || '', result[4] || ''];
    };

    // path.resolve([from ...], to)
    // posix version
    exports.resolve = function() {
        var resolvedPath = '',
            resolvedAbsolute = false;

        for (var i = arguments.length - 1; i >= -1 && !resolvedAbsolute; i--) {
            var path = (i >= 0) ? arguments[i] : process.cwd();

            // Skip empty and invalid entries
            if (typeof path !== 'string' || !path) {
                continue;
            }

            resolvedPath = path + '/' + resolvedPath;
            resolvedAbsolute = path.charAt(0) === '/';
        }

        // At this point the path should be resolved to a full absolute path, but
        // handle relative paths to be safe (might happen when process.cwd() fails)

        // Normalize the path
        resolvedPath = normalizeArray(resolvedPath.split('/').filter(function(p) {
            return !!p;
        }), !resolvedAbsolute).join('/');

        return ((resolvedAbsolute ? '/' : '') + resolvedPath) || '.';
    };

    // path.normalize(path)
    // posix version
    exports.normalize = function(path) {
        var isAbsolute = path.charAt(0) === '/',
            trailingSlash = path.slice(-1) === '/';

        // Normalize the path
        path = normalizeArray(path.split('/').filter(function(p) {
            return !!p;
        }), !isAbsolute).join('/');

        if (!path && !isAbsolute) {
            path = '.';
        }
        if (path && trailingSlash) {
            path += '/';
        }

        return (isAbsolute ? '/' : '') + path;
    };


    // posix version
    exports.join = function() {
        var paths = Array.prototype.slice.call(arguments, 0);
        return exports.normalize(paths.filter(function(p, index) {
            return p && typeof p === 'string';
        }).join('/'));
    };


    // path.relative(from, to)
    // posix version
    exports.relative = function(from, to) {
        from = exports.resolve(from).substr(1);
        to = exports.resolve(to).substr(1);

        function trim(arr) {
            var start = 0;
            for (; start < arr.length; start++) {
                if (arr[start] !== '') break;
            }

            var end = arr.length - 1;
            for (; end >= 0; end--) {
                if (arr[end] !== '') break;
            }

            if (start > end) return [];
            return arr.slice(start, end - start + 1);
        }

        var fromParts = trim(from.split('/'));
        var toParts = trim(to.split('/'));

        var length = Math.min(fromParts.length, toParts.length);
        var samePartsLength = length;
        for (var i = 0; i < length; i++) {
            if (fromParts[i] !== toParts[i]) {
                samePartsLength = i;
                break;
            }
        }

        var outputParts = [];
        for (var i = samePartsLength; i < fromParts.length; i++) {
            outputParts.push('..');
        }

        outputParts = outputParts.concat(toParts.slice(samePartsLength));

        return outputParts.join('/');
    };

}


exports.dirname = function(path) {
    var result = splitPath(path),
        root = result[0],
        dir = result[1];

    if (!root && !dir) {
        // No dirname whatsoever
        return '.';
    }

    if (dir) {
        // It has a dirname, strip trailing slash
        dir = dir.substring(0, dir.length - 1);
    }

    return root + dir;
};


exports.basename = function(path, ext) {
    var f = splitPath(path)[2];
    // TODO: make this comparison case-insensitive on windows?
    if (ext && f.substr(-1 * ext.length) === ext) {
        f = f.substr(0, f.length - ext.length);
    }
    return f;
};


exports.extname = function(path) {
    return splitPath(path)[3];
};


exports.exists = function(path, callback) {
    process.binding('fs').stat(_makeLong(path), function(err, stats) {
        if (callback) callback(err ? false : true);
    });
};


exports.existsSync = function(path) {
    try {
        process.binding('fs').stat(_makeLong(path));
        return true;
    } catch (e) {
        return false;
    }
};


var _makeLong = exports._makeLong = isWindows ?
    function(path) {
        path = "" + path;
        if (!path) {
            return "";
        }

        var resolvedPath = exports.resolve(path);

        if (resolvedPath.match(/^[a-zA-Z]\:\\/)) {
            // path is local filesystem path, which needs to be converted
            // to long UNC path.
            return '\\\\?\\' + resolvedPath;
        } else if (resolvedPath.match(/^\\\\[^?.]/)) {
            // path is network UNC path, which needs to be converted
            // to long UNC path.
            return '\\\\?\\UNC\\' + resolvedPath.substring(2);
        }

        return path;
    } :
    function(path) {
        return path;
    };
